l3mdev_maste...by_index_rcu(9)

💅 l3mdev_master_upper_ifindex_by_index_rcu(9) 💅

okay so bestie, we're in the Kernel API Manual today and this one's a lil function with a very long name, but she's iconic and honestly not that deep 🎀

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✨ NAME ✨

l3mdev_master_upper_ifindex_by_index_rcu — get the index of the upper l3 master device 🦋

like, you want the boss device's index? this is the girl that gets it for you. no cap.

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🌸 SYNOPSIS 🌸

int l3mdev_master_upper_ifindex_by_index_rcu (struct net *net , int ifindex );

yes that's the whole signature, she said "short and sweet" and then gave us a hyphen-heavy name anyway 😭💀

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🔥 ARGUMENTS 🔥

• net — the network namespace we're doing the device index lookup in. it's giving "where are we even looking" energy 🌈
• ifindex — the targeted interface. the one we're asking about, the main character 🎀

🫶 quick vibe check: net = which namespace, ifindex = which interface. two args, that's it, we love a low-effort date periodt.

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👑 SEE ALSO 👑

• the kernel file ./net/l3mdev/l3mdev.c — where she actually lives 💖
• l3mdev_master_ifindex_rcu(9)
• l3mdev_fib_table_rcu(9)
• l3mdev_link_scope_lookup(9)
• l3mdev_fib_rule_match(9)

all her besties fr fr, go say hi 💅

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✨ mwah ✨ that's the page! sourced from ./net/l3mdev, dated October 2026 — literally stamped and everything. slay, go read the man page and remember to hold the RCU lock, iykyk 🧚💜